On December 22nd, 2003, the Mw=6.5 San Simeon earthquake occurred 12 kilometers east of San Simeon, California, causing damage to buildings, roads, and other infrastructure throughout the central coast. The community of Oceano, 80 kilometers southeast of the epicenter, experienced damage to foundations, roads, and utilities due to liquefaction and lateral spreading. The unique geologic environment in Oceano caused a local amplification of ground motions, liquefaction, and lateral spreading. This study entailed developing ten liquefaction case histories from Oceano during the 2003 San Simeon earthquake. Four of the ten case histories are liquefaction cases and six are non-liquefaction cases, with Cyclic Stress Ratio (CSR) ranging from 0.17 to 0.43 and average corrected cone tip resistance (qc1) ranging from 2.67 to 23.53 kN/m^2. Subsurface data used to represent the geologic conditions in each case history included CPT soundings provided by the United States Geological Survey (Holzer et al., 2004). Ground motion data used to represent the earthquake conditions in each case history included the nearest relatively free field ground motion recordings from the SLO Rec Center Seismic Monitoring Station provided by the PEER strong motion center (PEER Ground Motions Database, 2003). CPT soundings were grouped together to develop representative case histories, allowing for averaging of parameters. The stratum with the single highest potential for liquefaction was selected and used as the ‘critical layer’ in each case history. To accurately represent the ground motion felt by each critical layer, a site response model was used to calculate average shear stress, which was used to calculate Cyclic Stress Ratio. The site response model was built using DEEPSOIL V6.1 with measured seismic shear wave velocities. Velocities were measured using passive geophysical methods in conjunction with Spatial Autocorrelation (SPAC) methods to process the data into shear wave velocity profiles. Measured velocities ranged from approximately 117 to 469 meters per second at depths ranging from 0 to 50 meters below the ground and were normally dispersive.

[pt] O fenômeno de liquefação continua sendo um dos temas mais importantes, complexos e controversos da engenharia geotécnica, sendo a liquefação dinâmica, causada por terremotos, o maior contribuinte de risco sísmico urbano em vários países andinos. O movimento causa incrementos da poropressão que reduz a tensão efetiva e conseqüentemente a resistência ao cisalhamento de solos arenosos. O presente trabalho de pesquisa apresenta e compara algumas das metodologias existentes para a avaliação do fenômeno de liquefação dinâmica, variando desde o método semi-empírico de Seed-Idriss para estimativas do potencial de liquefação até a execução de algumas análises numéricas, no contexto dinâmico, através do programa computacional FLAC 2D v.5. Um estudo de caso, para uma comparação dos diversos procedimentos, consiste na análise dinâmica de uma pilha de lixiviação de minério de cobre, situada em região de atividade sísmica no Peru que, devido a problemas no sistema de drenagem interna, resultou com um alto nível de saturação que poderia colocar sua estabilidade em risco devido à possibilidade de liquefação sob carregamento sísmico. Dos resultados obtidos nessas análises, pode-se afirmar que o método semi-empírico de Seed-Idriss, para determinação do potencial de liquefação, compara-se bastante bem com modelos mais sofisticados baseados em análises dinâmicas empregando tanto o modelo constitutivo de Finn quanto o modelo constitutivo elastoplástico UBCSAND. / [en] The phenomenon of liquefaction is still one of the most important, complex and controversial subjects of the geotechnical engineering, being the dynamic liquefaction, caused by earthquakes, the major contributor to urban seismic risks in several Andesian countries. The shaking increases the pore water pressure which reduces the soil effective stress and, therefore, the shear strength of sandy soils. This dissertation presents and compares some of the proposed methodologies to evaluate the phenomenon of dynamic liquefaction, ranging from the semi-empirical method of Seed-Idriss to estimate the liquefaction potential to the execution of some numerical analyses, within the dynamic context, through the computational program FLAC 2D v.5. The case study, for the comparison among the several procedures, consists of a copper ore heap leach, situated in a high seismic activity zone in Peru, that experimented high levels of saturation, due to problems in the internal drainage system, that could put in risk the stability of the leach pad to the possibility of liquefaction under seismic loading. From the results of such analyses, one can say that the semi-empirical method proposed by Seed- Idriss for the determination of the liquefaction potential compares quite well with outputs from more sophisticated numerical analyses based on dynamic studies that incorporate either the Finn s or the elasto-plastic UBCSAND constitutive models.

Tee present research focuses on seismic hazard studies for the states of Tripura and Mizoram in the North-East India with taking into account the complex sesismotectonic characteristics of the region. This area is more prone to earthquake hazard due to complex subsurface geology, peculiar topographical distribution, continuous crustal deformation due to the under thrusting of Indian and the Eurasian plates, a possible seismic gap, and many active intraplate sources identified within this region. The study area encompasses major seismic source zones such as Indo Burmese Range (IBR), Shillong Plateau (SP), Eastern Himalayan arc (EH), Bengal Basin (BB), Mishmi Thrust (MT) and Naga Thrust (NT). Five historical earthquakes of magnitude Mw>8 have been listed in the study area and 15 events of magnitude Mw>7 have occurred in last 100 years. Indian seismic code BIS-1893-2002 places the study area with a high level of seismic hazard in the country (i.e. seismic zone V). More than 60% of the area is hilly steep-terrain in nature and the altitude varies from 0 to 3000 meters. Recent works have located a seismic gap, known as the Assam gap since 1950 between the EH, SP, and IBR with the Eurasian plate. Various researchers have estimated the return period, and a large size earthquake is expected in this region any time in future. The area is also highly prone to liquefaction, since rivers in Tripura (Gomati, Howrah, Dhalai, Manu, Bijay, Jeri, Feni) and the rivers in Mizoram (Chhimtuipui, Tlawng, Tut, Tuirial and Tuivawl etc.) are scattered throughout the study area where soil deposits are of sedimentary type. In 2011, both the states together have experienced 37 earthquakes (including foreshocks and aftershocks) with magnitudes ranging from 2.9 to 6.9. Of these events, there were 23 earthquakes (M>4) of magnitudes M6.4 (Feb 4th 2011), M6.7 (March 24th 2011), M6.9 (Sept.18th 2011), M6.4 (October 30th 2011), M6.9 (Dec 13th 2011), M5.8 (Nov 21st 2011), M5 (Aug 18th 2011), M4.9 (July 28th 2011), M4.6 (Dec 15th 2011), M4.6 (Jan 21st 2011), M4.5 (Dec 9th 2011), M4.5 (Oct 21th 2011), M4.5 (Oct 17th 2011), M4.5 (Sept 18th 2011), M4.3 (Oct 10th 2011), M4.3 (Sept 22nd 2011), M4.3 (April 4th 2011), M4.2 (Sept 9th 2011), M4.2 (Sept 18th 2011), M4.1 (April 29th 2011), M4.1 (Feb 22nd 2011), M4 (June 9th 2011), and M4 (Dec 2nd 2011) which occurred within this region [source: IMD (Indian Metrological Department), India]. The earthquake (M6.9) that occurred on Sept. 18th 2011 is known as the Sikkim earthquake, and it caused immense destruction including building collapse, landslides, causalities, disrupted connectivity by road damages and other infrastructural damages in Sikkim state as well as the entire North-East India. In the cities of Agartala and Aizawl of Tripura and Mizoram, construction of high rise building is highly restricted by the Government. Being the capital city, many modern infrastructures are still pending for growth of the city planning. Although many researchers have studied and reported about the status of seismicity in North-East Region of India, very few detailed studies have been carried out in this region except Guwahati, Sikkim and Manipur where almost the whole of the study area is highly vulnerable to severe shaking, amplification, liquefaction, and landslide. From the available literature, no specific study exists for Tripura and Mizoram till date. In the present research, seismic hazard assessment has been performed based on spatial-temporal distribution of seismicity and fault rupture characteristics of the region. The seismic events were collected from regions covering about 500 km from the political boundary of the study area. The earthquake data were collected from various national and international seismological agencies such as the IMD, Geological Survey of India (GSI), United State Geological Survey (USGS), and International Seismological Centre (ISC) etc. As the collected events were in different magnitude scales, all the events were homogenized to a unified moment magnitude scale using recent magnitude conversion relations (region specific) developed by the authors for North-East Region of India. The dependent events (foreshocks and aftershocks) were removed using declustering algorithm and in total 3251 declustered events (main shocks) were identified in the study area since 1731 to 2011. The data set contains 825 events of MW < 4, 1279 events of MW from 4 to 4.9, 996 events MW from 5 to 5.9, 131 events MW from 6 to 6.9, 15 events MW from 7 to 7.9 and 5 events MW ≥8. The statistical analysis was carried out for data completeness (Stepp, 1972). The whole region was divided into six seismic source zones based on the updated seismicity characteristics, fault rupture mechanism, size of earthquake magnitude and the epicentral depth. Separate catalogs were used for each zone, and seismicity parameters a and b were estimated for each source zone and other necessary parameters such as mean magnitude (Mmean), Mmax, Mmin, Mc and recurrence periods were also estimated. Toposheets/vector maps of the study area were collected and seismic sources were identified and characterized as line, point, and areal sources. Linear seismic sources were identified from the Seismotectonic atlas (SEISAT, 2000) published by the GSI, in addition to the source details collected from available literature and remote sensing images. The SEISAT map contains 43 maps presented in 42 sheets covering entire India and adjacent countries with 1:1million scale. Sheets representing the features of the study area were scanned, digitized and georeferenced using MapInfo 10.0 version. After this, tectonic features and seismicity events were superimposed on the map of the study area to prepare a Seismotectonic Map with a scale of 1:1million. In seismic hazard assessment, a state of art well known methodologies (deterministic and probabilistic) was used. In deterministic seismic hazard analysis (DSHA) procedure, hazard assessment is based on the minimum distance between sources to site considering the maximum magnitude occurred at each source. In hazard estimation procedure a lot of uncertainties are involved, which can be explained by probabilistic seismic hazard analysis (PSHA) procedure related to the source, magnitude, distance, and local site conditions. The attenuation relations proposed by Atkinson and Boore (2003), and Gupta (2010) are used in this analysis. Because in this region two type activities are mostly observed, regions such as SP, and EH are under plate boundary zone whereas IBR is under subduction process. These equations (GMPEs) were validated with the observed PGA (Peak ground acceleration) values before use in the hazard evaluation. The hazard curves for all six major sources were prepared and compiled to get the total hazard curve which represents the cumulative hazard of all sources. Evaluation of PGA, Sa (0.2s and 1.0s) parameters at bedrock level were estimated considering a grid size of 5 km x 5 km, and spectral acceleration values corresponding to a certain level of probability (2% and 10%) were done to develop uniform hazard spectrum (UHS) for both the cities (Agartala and Aizawl). To carry out the seismic microzonation of Agartala and Aizawl cities, a detailed study using geotechnical and geophysical data has been carried out for site characterization and evaluation of site response according to NEHRP (National Earthquake Hazard Response Program) soil classifications (A, B, C, D, and E-type). Seismic site characterization, which is the basic requirement for seismic microzonation and site response studies of an area. Site characterization helps to have the idea about the average dynamic behavior of soil deposits, and thus helps to evaluate the surface level response. A series of geophysical tests at selected locations have been conducted using multichannel analysis of surface waves (MASW) technique, which is an advanced method to obtain direct shear wave velocity profiles from in situ measurements for both the cities. Based on the present study a major part of Agartala city falls under site class D, very few portions come under site class E. On the other hand, Aizawl city comes under site class C. Next, a detailed site response analysis has been carried out for both the cities. This study addresses the influence of local geology and soil conditions on incoming ground motion. Subsurface geotechnical (SPT) and geophysical (MASW) data have been obtained and used to estimate surface level response. The vulnerable seismic source has been identified based on DSHA. Due to the lack of strong motion time history of the study area, synthetic ground motion time histories have been generated using point source seismological model (Boore 2003) at bedrock level based on fault rupture parameters such as stress drop, quality factor, frequency range, magnitude, hypocentral distance etc. Dynamic properties such as the shear modulus (G) and damping ratios (ζ) have been evaluated from the soil properties obtained from SPT bore log data collected from different agencies such as PWD (Public works Department), and Urban Development Dept. of the State Government, in situ shear wave velocity has been obtained from MASW survey in different locations, and following this, a site response analysis has been carried out using SHAKE-2000 to calculate the responses at the ground surface in combination of different magnitudes, distances and epicentral depth for a particular site class. An amplification factor was estimated as the ratio of the PGA at the ground surface to the PGA at bedrock level, a regression analysis was carried out to evaluate period dependant site coefficients, and hence, the period dependant hazard impact on the ground surface could be calculated to obtain the spatial variation of PGA over the study area. Further, liquefaction potential of the site (Agartala) was also evaluated using available SPT bore log data collected and using presently estimated surface level PGA. The results are presented in the form of liquefaction hazard map representing as a Factor of safety (FS) against liquefaction with various depths such as 1.5m, 10m, and 15m respectively. It has been seen that Agartala city shows highly prone to liquefaction even up to 15 m depth. Hence, site specific study is highly recommended for implementing any important project. The liquefaction hazard assessment could not be conducted for the Aizawl city because of non availability of the SPT-N data, however, the city stands on hills/mountains, and therefore, such a study is not applicable in this area. Further, seismic microzonation maps for both the cities have been prepared considering Analytical Hierarchy Process (AHP) which support to the Eigen value properties of the system. Two types of hazard maps have been developed, one using deterministic and another using the probabilistic seismic microzonation maps. These maps can be directly used as inputs for earthquake resistant design, and disaster mitigation planning of the study area. However, an investigation has also been made in forecasting a major earthquake (Mw>6) in North-East India using several probabilistic models such as Gamma, Weibull and lognormal models. IBR and EH show a high probability of occurrences in the next 5 years (i.e. 2013-2018) with >90% probability.

Soil improvement methods are used to minimize the consequences of liquefaction by changing the characteristics and/or response of a liquefiable soil deposit. When considering sites with previous development, the options for soil improvement are limited. Traditional methods, such as compaction and vibratory techniques, are difficult to employ because of adverse effects on adjacent structures. One potential method for soil improvement against soil liquefaction in developed sites is accelerated drainage through in situ vertical drains. Vertical drains expedite the dissipation of excess pore water pressures by reducing the length of the pore water drainage path. For more than thirty years, vertical gravel drains or stone columns have been employed to ensure the excess pore water pressure ratio remains below a prescribed maximum value. In recent years, the use of prefabricated vertical drains (PVDs) has increased because the drains can be installed with less site disruption than with traditional soil improvement methods. To date, little-to-no field or experimental verification is available regarding the seismic performance of sites treated with PVDs. The effectiveness of PVDs for liquefaction remediation was evaluated via small-scale centrifuge testing and full-scale field testing. A small-scale centrifuge test was performed on an untreated soil deposit and on a soil deposit treated with small-scale vertical drains. Compared to the untreated condition, the presence of the small-scale vertical drains provided numerous benefits including smaller magnitudes of excess pore water pressure generation and buildup, smaller induced cyclic shear strains, reduced times for pore pressure dissipation, and smaller permanent horizontal and vertical displacements. In addition, full-scale in situ field experiments were performed in an untreated soil deposit and in a soil deposit treated with full-scale PVDs using a vibrating mandrel as the dynamic source. In the untreated test area, the maximum induced excess pore pressure ratio reached about 0.95. In the treated test area, the vibratory installation of the first few drains generated significant excess pore pressures; however, significant excess pore pressures were not generated during the vibratory installation of additional drains because of the presence of the adjacent drains. Additionally, the vibratory installation of the drains caused significant settlement and significantly altered the shear wave velocity of the sand. Dynamic shaking after installation of all of the drains induced small accelerations, small cyclic shear strains, and negligible excess pore water pressures in the soil. The results of the field experiment indicate that the prefabricated vertical drains were effective at dissipating excess pore water pressures during shaking and densifying the site. / text

This study is focused on developing a method to predict the dynamic behavior of mine tailings dams under earthquake loading. Tailings dams are a by-product of coal mining and processing activities. Mine tailings impoundments are prone to instability and failure under seismic loading as a result of the mechanical behavior of the tailings. Due to the existence of potential seismic sources in close proximity to the coal mining regions in the United States, it is necessary to assess the post-earthquake stability of these tailings dams. To develop the aforementioned methodology, 34 cyclic triaxial tests along with vane shear tests were performed on undisturbed mine tailings specimens from two impoundments in Kentucky. Therefore, the liquefaction resistance and the residual shear strength of the specimens were measured. The laboratory cyclic strength curves for the coal mine specimens were produced, and the relationship between plasticity, density, cyclic stress ratio, and number of cycles to liquefaction were identified. The samples from the Big Branch impoundment were generally loose samples, while the Abner Fork specimens were dense samples, older and slightly cemented. The data suggest that the number of loading cycles required to initiate liquefaction in mine tailings, NL, decreases with increasing CSR and with decreasing density. This trend is similar to what is typically observed in soil. For a number of selected specimens, using the results of a series of small-strain cyclic triaxial tests, the shear modulus reduction curves and damping ratio plots were created. The data obtained from laboratory experiments were correlated to the previously recorded geotechnical field data from the two impoundments. The field parameters including the SPT blow counts (N1)60, corrected CPT cone tip resistance (qt), and shear wave velocity (vs), were correlated to the laboratory measured cyclic resistance ratio (CRR). The results indicate that in general, the higher the (N1)60 and the tip resistance (qt), the higher the CSR was. Ultimately, practitioners will be able to use these correlations along with common state-of-practice geotechnical field methods to predict cyclic resistance in fine tailings to assess the liquefaction potential and post-earthquake stability of the impoundment structures.

[pt] Mudanças das propriedades dos solos devido à ação de carregamentos dinâmicos são responsáveis por danos significativos em geo-estruturas, tais como: barragens, estruturas de concentração, fundações, taludes, etc. A ocorrência do fenômeno da liquefação, em materiais suscetíveis como areias fofas saturadas, representa um tipo de resposta desastrosa de solos. O termo liquefação tem sido empregado para descrever uma variedade de fenômenos no qual tem em comum o desenvolvimento de altas poropressões em materiais saturados sem coesão devido a carregamentos monotônicos , transientes ou ciclios. A previsão da liquefação depende de uma adequada análise do comportamento não-drenado do material, em termos do incremento de poropressões e da perda da rigidez da mistura sólido-fluido, durante e após o período de movimento. O estabelecimento das equações governantes é essencial para elaboração de um modelo matemático realista para descrever o comportamento físico deste fenômeno. As equações a srem consideradas são: equação de movimento da fase sólida, a equação do movimento da mistura sólido-fluido , a equação de continuidade da fase fluida, as equações de acoplamento das fases e as equações constitutivas desses materiais. Nesta tese a resposta dinâmica do solo foi investigada numericamente mediante a técnica dos elementos finitos. A discretização espacial das equações governantes foi feita através de método de Galerkin e a discretização temporal pelo método de Newmark Generalizado. Um modelo constitutivo elasto-plástico foi considerado para descrever o comportamento mecânico da fase sólida, desenvolvido a partir de conceitos da generealização da teoria da plasticidade, que apresenta algumas vantagens em relação aos outros modelos baseados na teoria da plasticidade clássica. A implementação computacional foi escrito em fortran 90. Exemplos numéricos analisados nesta tese comprovam tanto a eficiência do modelo constitutivo na predição do comportamento do solo sobre liquefação como a confiabilidade do programa computacional elaborado nesta pesquisa, em termos da rapidez de processamento e da boa precisão dos resultados, quando comparados com soluções analíticas e outros valores numéricos obtidos por vários autores e diferentes modelos constitutivos. / [en] Changes in soil properties due to the action of dynamic loads are responsible for significant damage of geo-structures such as dams, retaining structures,building foundations, slopes, etc. The occurrence of liquefaction phenomena in susceptible materials, such as loose saturated, represents a type of disastrous response of soil, the term liquefaction has been used to refer to a group of phenomena wich have in common the development of high pore pressures in saturated cohesionless mterial due to monotonic, transient, or cyclic loads. The prediction of soil liquefaction depends of an adequate analysis of the behavior of undrained materials, in terms of increase of pore water pressure and weakening of the solid-fluid mixture, during and after the periodic motion. The establishment of the governing equations is essential to provide a realistic mathematical model to describe the physical behavior of this phenomenon. The system of equations to be considered are: the equilibrium equation of the solid phase, the equilibrium equation of the solid-fluid mixture, the conservation mass of the fluid phase, the coupling equation of phases, and the conservation equations of materials. In this thesis the soil dynamic response was numerically investigated by the finite element method. To obtain the spatial discretization in time was the Generalized Newmark method. An elastic-plastic constitutive model was used to describe the mechanical behavior of the solid phase. This model was developed in the framework of the generalized theory of plasticity, wich has some advantages when compared with other models based on the classical plasticity theory. The computacional implementation was written in fortran 90. Numerical examples considered in this thesis demonstrate the efficiency of the constitutive model to simulated the predicted behavior of soil under liquefaction as well as the reliability of the software developed in this research, in terms of computational effort and good accuracy of the results, when compared with some analytical solutions and other numerical values obtained by various authors and different constitutive models.

Heavy-duty trucks accounts for 25% CO2 emissions in Sweden and there is approximately 12.6 million heavy-duty vehicles in the EU with different types of fuel and utilization areas. EU is implementing increased legislations to reduce emissions and increase the use of biofuel and members of the EU is starting to ban the use of diesel trucks in local areas, which drives the need to find other suitable fuel. Therefore, to study and compare the emissions and energy demand in the heavy-duty truck industry a case study is created. Which focuses on production and processing, transportation, distribution and fuel consumption. Cultivation of maize and anaerobic digestion of maize, waste and manure is included as well. Data gathered from the collaboration between the European Commission’s Joint Research Centre, eucar and Concawe (JEC) is used to create scenarios and these are validated with previous studies. The case study includes seven LNG cases, three LBG cases and two diesel cases together with several other cases collected for verification. Furthermore, potential boil-off and leakage during maintenance is included to further estimate the possible emissions correlated with LNG and LBG vehicles. The Well-to-Wheels analysis resulted in most LNG and LBG cases having higher energy input compared to diesel. LBG has the lowest emissions of greenhouse gases. The transportation method and distance are the most important aspects for the Well-to-Tank analysis. The fuel consumption is the main source of emissions and energy input in the Tankto-Wheels analysis. In conclusion, the transportation and fuel consumption are the greatest contributors of emissions and energy demand in the complete Well-to-Wheels analysis.

O processo de liquefação hidrotermal (HTL) pode converter diversos tipos de biomassa em óleo bruto. Além do produto principal, é gerado um efluente (PHWW) com elevada carga orgânica, quantidades altas de nutrientes e compostos tóxicos. Para lidar com este tipo efluente tem-se sugerido a combinação de tratamentos físico-químicos e biológicos. O objetivo deste estudo foi avaliar a aplicação de processos oxidativos (por H2O2 e fotocatálise com TiO2) e digestão anaeróbia no tratamento do efluente da liquefação hidrotermal de Spirulina. Inicialmente caracterizou-se o efluente em termos de carga orgânica, nutrientes e compostos nitrogenados cíclicos (CNC). Posteriormente, avaliou-se a concentração de oxidante e o tempo de reação no processo de oxidação com H2O2. O tratamento fotocatalítico foi então avaliada no tratamento do efluente em questão, isoladamente, em sequência e combinada ao processo de oxidação por ação de H2O2. Finalmente combinaram-se os processos de oxidação por ação de H2O2 e digestão anaeróbia no tratamento de efluente de PHWW. O efluente da liquefação hidrotermal de Spirulina apresentou elevada carga orgânica, pH alcalino e concentrações altas de nutrientes (nitrogênio e fósforo). Verificou-se também a presença de CNC como pirazinas, &delta;-valerolactama, caprolactama e butirolactama. A aplicação do processo oxidativo por H2O2 no tratamento de PHWW apresentou efeitos positivos, principalmente para a descoloração que atingiu 93,8 %. A eficiência máxima de remoção de DQO foi de 15,3%. Foi percebida também redução nas concentrações dos CNC. A eficiência do processo de oxidação avançada por fotocatálise e H2O2 foi maior do que obtida quando estes processos foram aplicados separadamente. A aplicação dos processos combinados apresentou eficiência de remoção de cor e DQO semelhante às obtidas quando os processos foram aplicados em sequência, propiciando economia de tempo de reação. Por fim, verificou-se que a digestão anaeróbia do efluente pré-tratado com H2O2 apresentou maior produção de CH4 e remoção de matéria orgânica quando comparada com a digestão anaeróbia que o efluente in natura. Assim, conclui-se a utlização de processos oxidativos avançados ou a combinação da oxidação por H2O2 com a digestão anaeróbia são alternativas promissoras para o tratamento da PHWW. / The hydrothermal liquefaction process (HTL) can convert various types of biomass into bio-crude oil. In addition to the main product, wastewater (PHWW) is generated with high organic content, high amounts of nutrients and toxic compounds. To cope with this type of wastewater the combination of physicochemical and biological treatments has been suggested. The aim of this study was to evaluate the application of oxidative processes (using H2O2 and photocatalysis with TiO2) and anaerobic digestion in the treatment of hydrothermal liquefaction of Spirulina wastewater. Firstly, PHWW was characterized in terms of organic matter, nutrients and nitrogen heterocyclic compounds (CNC) concentrations. Secondly, the oxidant concentration and the reaction time in the oxidation process using H2O2 was evaluated. Photocatalytic treatment was then tested isolated, in sequence and combinated with the oxidation processo using H2O2. Finally, oxidation with H2O2 and anaerobic digestion were combinated and evaluated. The PHWW showed high organic load, alkaline pH and high concentrations of nutrients (nitrogen and phosphorus). The presence of CNC as pyrazines, &delta;-valerolactam, caprolactam and butyrolactam was also verified. The application of the oxidative process using H2O2 showed positive effects mainly for color removal, which reached 93.8%. The maximum efficiency of COD removal was 15.3%. Reduction in CNC concentrations was also observed . The efficiency of the advanced oxidation process (by combining photocatalysis and H2O2) was greater than that obtained when these processes were applied separately. The application of the combined process presented color and COD removal efficiencies similar to those obtained when the processes were applied in sequence, allowing reaction time savings. Finally, the anaerobic digestion of pre-treated (with H2O2) PHWW showed a greater CH4 production and higher organic matter removal, compared to anaerobic digestion of in natura PHWW. Thus it is possible to conclude that the utlization of advanced oxidation processes or the combination of oxidation with H2O2 and anaerobic digestion are promising alternatives for the treatment of PHWW.

Este trabalho tem como objetivo analisar a tecnologia do ciclo refrigerante misto para obtenção de gás natural liquefeito (GNL). Nessa tecnologia, o GNL é obtido por meio do seu resfriamento através de um ciclo de refrigeração, cujo fluido refrigerante é formado por uma mistura de diversos componentes. O ciclo de refrigeração é usado para resfriar a corrente de gás natural até as condições criogênicas por meio de um trocador de calor. A determinação da composição ótima dessa mistura de refrigerantes é de suma importância para a correta e eficiente operação da planta. O modelo termodinâmico para o cálculo de equilíbrio de fases dos componentes da mistura refrigerante é o baseado na Lei de Raoult, válido para misturas e soluções ideais. Inicialmente, revisam-se os conceitos de refrigerantes mistos, curvas compostas e o ponto de pinça (pinch point), utilizados na implementação da solução computacional. A aplicação dos modelos de gás e solução ideal influencia nos resultados, mas, não obstante, produz bons resultados como os obtidos no presente trabalho. A operação eficiente do ciclo depende, sobretudo, de três parâmetros principais, quais sejam: vazão da mistura refrigerante, razão de pressões alta e baixa do ciclo de refrigeração e composição da mistura refrigerante. Da análise dos resultados obtidos conclui-se que a alteração nas proporções da composição do refrigerante muda significativamente a forma das curvas composta quente e composta fria, quando comparados à alteração dos níveis de pressão e da vazão do ciclo refrigerante. Entretanto, a operacionalização do ciclo somente ocorre se um dado conjunto de valores daqueles parâmetros satisfaça uma determinada diferença mínima de temperatura, ou ponto de pinça, entre as curvas composta quente e composta fria dentro do trocador de calor. Assim, a operação eficiente do ciclo de refrigeração requer a otimização daqueles três parâmetros operacionais. / This work has the objective of analyzing the technology of mixed refrigerant cycle for obtaining liquefied natural gas (LNG). In that technology, the liquefied natural gas is obtained by means of cooling through a refrigeration cycle, whose fluid refrigerant is formed by a mixture of various components. The refrigeration cycle is used to cool the natural gas stream to cryogenic condition with the use of a heat exchanger. The determination of the optimal composition of this refrigerant mixture is very important for the correct and efficient operation of the plant. The thermodynamic model for the equilibrium phase calculation of the refrigerant mixture is based on the Law of Raoult, which is valid for ideal mixtures and solutions. Initially, the concepts of refrigerant mixture, composite curves and pinch point used in the implementation of the numerical solution were reviewed. The application of ideal-gas and ideal-solution models has influence on the results. Nevertheless, it produces good results as those obtained in the present work. The efficient operation of the cycle depends essentially of three key parameters, which are: refrigerant flow rate, the ratio of high to low pressures of the refrigerant cycle and the mixed refrigerant composition. The results indicated that the composition variation of the refrigerant changes significantly the shape of hot and cold composite curves in comparison to the modification in the pressure levels and the refrigerant flow rate of the refrigerant cycle. However, the process will operate only if a given set of values of those parameters satisfies a minimum temperature difference, or pinch point, between the hot and cold composite curves within the heat exchanger. Thus, the efficient operation of the refrigerant cycle requires the optimization of those three operational parameters.

The cryogenic carbon capture™ (CCC) process provides energy- and cost-efficient carbon capture and can be configured to provide an energy storage system using an open-loop natural gas (NG) refrigeration system, which is called energy storing cryogenic carbon capture (CCC-ES™). This investigation focuses on the transient operation and especially on the dynamic response of this energy storage system and explores its efficiency, effectiveness, design, and operation. This investigation included four tasks.The first task explores the steady-state design of four different natural gas liquefaction processes simulated by Aspen HYSYS. These processes differ from traditional LNG process in that the CCC process vaporizes the LNG and the cold vapors return through the LNG heat exchangers, exchanging sensible heat with the incoming flows. The comparisons include costs and energy performance with individually optimized processes, each operating at three operating conditions: energy storage, energy recovery, and balanced operation. The second task examines steady-state and transient models and optimization of natural gas liquefaction using Aspen HYSYS. Steady-state exergy and heat exchanger efficiency analyses characterize the performance of several potential systems. Transient analyses of the optimal steady-state model produced most of the results discussed here. The third task explores transient Aspen HYSYS modeling and optimization of two natural gas liquefaction processes and identifies the rate-limiting process components during load variations. Novel flowrate variations included in this investigation drive transient responses of all units, especially compressors and heat exchangers. Model-predictive controls (MPC) effectively manages such heat exchangers and compares favorably with results using traditional controls. The last task shows how an unprocessed natural gas (NG) pretreatment system can remove more than 90% of the CO2 from NG with CCC technology using Aspen Plus simulations and experimental data. This task shows how CCC-based technology can treat NG streams to prepare them for LNG use. Data from an experimental bench-scale apparatus verify simulation results. Simulated results on carbon (CO2) capture qualitatively and quantitatively agree with experimental results as a function of feedstock properties.